[Guide] Air Cooling 101 – Fans

Fans

Welcome to the next edition of our Air Cooling 101 series of guides. In case you missed part 1 on CPU cooling, you can find it here. We move on to a topic in which there are consistently a lot of discussions around the net.

When we buy fans, we look at three main criteria:

1. CFM – Cubic Feet per Minute, or in simpler words, the amount of air that the fan can push/pull in a minute.
2. Static Pressure – The force with which the fan generates this airflow.
3. dBA – This is the sound rating of a fan and it gives you an idea of how quiet or noisy a fan is.

Most manufacturers tend to publish data on their fan’s with respect to these three criteria, however, most of the figures quoted by manufacturers tend to be a bit optimistic and I would take them with a pinch of salt.

With these basics in place, let us now take a quick look at the type of fans that are currently available in the market:

1. Sleeve Bearings – The cheapest to produce; most of the budget fans are made with sleeve bearings. The fan motor basically has two cylinders with a lubricant in between. The inner cylinder is covered with the lubricant and the fan runs when the inner cylinder turns within the outer one. This type of bearing, while initially fairly quiet, does tend to get noisier as it gets older and can also fail completely over time.

2. Ball Bearings – These fans use a ball bearing inside a pair of metal rings to turn the the fan blades. Ball bearing fans are more resilient over time and tend to last longer than sleeve bearing fans of a similar profile. The downside is that it’s also slightly more noisy. The quality of the bearings and lubricant are the two most important factors for this type of fan.

3. Fluid Bearing – Fluid bearings are made with two cylinders separated by a thin layer of liquid or gas. Since these surfaces do not make contact with each other, they tend to have an almost unlimited life and require very little maintenance. They are also relatively quiet as compared to the above two types.

4. Magnetic bearing – A magnetic bearing uses magnetic levitation caused by similar poles to keep the two sleeves apart. Again, these types of fans are very quiet and in theory have an unlimited life, as there is no contact between the sleeves. These are the most expensive of the lot .

Before we get into specific fan models that we recommend, it is important to note the most commonly used fans in a computer chassis, from an enthusiast point of view:

1. 120 x 25mm – This is the most common size that we see in a computer, either as case fans or for use as heat sink fans.

2. 120 x 38mm – This size is mainly used for heat sinks. The extra width of the fan’s case or shell helps to create more air pressure and therefore provide better cooling.

3. 140 x 25mm – These are used mainly as case fans as most heat sinks are not large enough to accept them. There are 140mm fans that have the 120mm type mounting points and are compatible with a large number of heat sinks and cases. The advantage of 140mm fans is that they need far fewer revolutions per minute to push the same amount of air as a 120mm fan of similar CFM rating can. This essentially leads to lower noise levels.

With the basics covered, we can start by looking at some of the fans that we suggest you use with a heat sink.

Heat Sink Fans

38mm

1. Sanyo Denki 109R H1011 – These are probably some of the most sought after fans for heat sink use and are considered the best amongst it’s peers, simply because it’s high static pressure at almost 6.6mm H2O and it’s acceptable noise levels. It puts out close to 102 CFM and is relatively quiet for this kind of airflow at 39dBA. Most of the extreme air coolers around the net will vouch for it’s performance. Extremely difficult to find at a decent price.

2. Delta AFB1212HHE – Rated at 120 CFM and 44dBA, these fans can push air at an amazing 9mm H2O. These are lot more noisy for daily use and need to be controlled with a fan controller if you intend to keep your hearing intact. They are great value for the money.

There are a lot of other fans in this section, specifically Scythe Ultra Kaze’s and Panaflo’s, but these are the two that we have tested and have found to be extremely good. Any one of these would be capable of providing approximately the same amount of cooling that a pair of 25mm fans in a push/pull arrangement would provide.

25 mm

Now lets take a look at the 25 mm list.

1. Scythe Gentle Typhoons D1225C12B4AP-15 – The very high speed version has probably the best noise to airflow/pressure ratios available on the market today. They are very quiet, and while they do not move a lot of air in CFM terms, they do move the air with a decent amount of pressure. They are also highly rated for use with radiators. The very high speed version pushes around 58 CFM at a quiet 28dBA and runs on a hydro bearing. I could really go on and on about these fans as they are my personal favorites at the moment.

2. Delta AFC1212SH – PWM – A high speed, loud fan, but in the 25mm variety. Does a great job on heat sinks and is a PWM fan to boot, so you can turn it down using either your bios options or other software. It pushes close to 113 CFM at 46.5 dBA. Great for those who don’t have fan controllers.

3. Cooler Master Excalibur – Great fans, but a bit expensive for what they are. They have probably the best accessories package in this list as well as removable blades for cleaning. They are a bit noisy at full speed, but work well with fan controllers. They do about 86 CFM at 2000 rpm and most of the noise is generated due to the open air design of the frame more than the motor. These fans come with barometric ball bearings, which are somewhere between the ball bearing models and the magnetic models.
Link to product: Cooler Master Excalibur

4. Yateloon High Speed D12SH-12 – Another superb fan, though it can also get a bit noisy. They come with closed ended corners, so a bit of modding may be required to attach them to a heat sink or radiator. They run silently when undervolted and they don’t have any clicking sounds when turned down. Pushing 88 CFM at around 40dBA, these run on sleeve bearings.

This is a fairly comprehensive list of the fans that we have tested within the last 12 months and should work well with any air cooling heat sink setup or water cooling radiator.

Case Fans

The reason for having a separate sub section for case fans is that while all of the above would work well as case fans, high air pressure is not generally needed in open air. Low pressure, high CFM fans generally work fine and therefore, you should not need to spend as much on high pressure 38mm fans. This is a list of fans that we have tested in the past and have found to be excellent at increasing air flow in a case.

1. Cooler Master R4 – They come in three different colors, with wonderful translucent cables and push close to 90 CFM. What more could you ask for in a case fan with some bling? They tend to be a bit noisy on side panels, but otherwise they are quite decent in terms of noise levels, but don’t believe the official rating of 19dBA or the manufacturer stated CFM numbers. Great, cheap case fans which are readily available.

2. Yateloon Medium Speed D12SM-12 – Great fans and very cheap at that. They are a lot less noisy than their higher flowing brothers and do a wonderful job as case fans, as well as heat sink fans. Easily one of the cheapest options around. Remember that these are sleeve bearing fans, so some amount of motor whine is to be expected.

3. Xigmatek XLF-F1253 – Very quiet, these fans push a decent amount of air and have all the bling that you could want. They come in a couple of different colors, so you can match them to whatever theme you are using in your case. Great case fans, but not so good when strapped on to a heat sink.

4. Enermax Apollish – Again, great fans with a whole lot of bling. They come in three different colors and most modders should love the style quotient. The only thing I don’t like about these fans are the thermal controls. They push about 71 CFM at full tilt and are a bit noisy when running at max.